You don't actually ``trap'' a control character. Instead, that character
generates a signal which is sent to your terminal's currently foregrounded
process group, which you then trap in your process. Signals are documented
in Signals and chapter 6 of the Camel.

Be warned that very few
C libraries are re-entrant. Therefore, if you attempt to
print() in a handler that got invoked during another stdio operation your internal structures will likely be in an inconsistent state, and your program will dump core. You can sometimes avoid this by using
syswrite() instead of
print().

Unless you're exceedingly careful, the only safe things to do inside a signal handler are: set a variable and exit. And in the first case, you should only set a variable in such a way that
malloc() is not called (eg, by setting a variable that already has a value).

However, because syscalls restart by default, you'll find that if you're in a ``slow'' call, such as
<FH>,read(),connect(), or
wait(), that the only way to terminate them is by ``longjumping'' out; that is, by raising an exception. See the time-out handler for a blocking
flock() in
Signals or chapter 6 of the Camel.